Chemistry is a great and complex subject. It is a of substances, their properties(пропртииз) and the reactions that change them into other substances
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- 2.Elements and Compounds.
- 3. D. I. Mendeleyev
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1.4.Chemistry Chemistry is a great and complex subject. It is a of substances, their properties(пропртииз) and the reactions that change them into other substances. Substances may exist (игзест) as solids(соледс), liquids (ликуидс) or gases(гасес). Sulphur(салфа), iron(аирон) and silver(силвэр) are solids(соледс) at an ordinary substance. Bromine and mercury(ˈmərkyərē) are liquids in the same conditions(кандишинс) and oxygen(ˈäksəjən) and hydrogen(hīdrəjən) are gases. But solid(солед) substance may become liquids if we heat(хэт) them to a proper (ПРОПЭ) temperature. Elements may be metallic (məˈtalik) and non-metallic. Nitrogen and carbon are non-metals, but lead and tin are metals. 2.Elements and Compounds. All substances can be divided (дивайдет) into two great classes, namely(nāmlē), elements and compounds(компаунс). An element is an indecomposable (indиkəmˈpōzəb(ə)l) substance, all compounds are substances, which consist(консист) of two or more different substances, and so they can be decomposed into two or more (môr) simple substances. Water can be decomposed into oxygen and hydrogen. Elements may be metallic and non-metallic. Nitrogen and carbon are non- metals, but lead and tin are metals. 3. D. I. Mendeleyev D. I. Mendeleyev, the great Russian scientist(сайнтест), was born(боун) in Tobolsk in 1834. After finishing school, at the age of 16, he went to St. Petersburg and entered(энтед) the Pedagogical (подигогикол инстут) Institute. He graduated from the Institute(инстут) in 1855. In 1866 Mendeley000100000000000000000000000000000000000000000000000000000000000000000000000000000ev was appointed professor at the University where he gave a course (коуст) of lectures (лакчест) on chemistry. At the University Mendeleyev taugh(тоут) classes(классес) in the morning. In the afternoon he made experiments in his two room laboratory. At night(найт) Mendeleyev spent much of his time working with the cards on which he put down information about each of the chemical elements. He made thousands of calculations(калкулайшнс), wrote a lot of letters, studied (стадит) many reports. In 1869 the description of more than 60 elements was completed, and Mendeleev published his Periodic Table (преидэк тэбл). He died (дайд) in February 1907 at the age of 75. жүктеу/скачать 22 Kb. Достарыңызбен бөлісу:
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